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Friday, July 2, 2010

Have ever touched the ac adapter for laptop after using for a long time? Maybe you will be hurt by the heat. As it has been controlled by well-designed circuits, it is unnecessary for you to worry about if the laptop charger will be fired. As long as the temperature of is with normal limits, you would be in no danger.

Then what causes the heat of laptop charger?

The principle of laptop charger is to transfer the mains supply to nominal power. In the process, except for output power, part of the energy is consumed by the adapter itself. Most of the consumed energy is the radiated heat while others are in the form of wave, usually called radiation wave. Of course, it doesn’t mean that an adapter with higher output power will produce more heat.

Every ac adapter has its own conversion efficiency. Nowadays, most of the adapters can reach about 75%-85% in conversion efficiency. In the process of manufacturing, the temperature has been controlled in an appropriate range just like the protection circuit to laptop battery. Furthermore, most of ac adapters are designed with high temperature resistant components.

How to control the temperature of laptop charger?

First, the laptop charger with higher conversion efficiency seems to be better. Therefore, less power is consumed in heat emission.

Next, lower internal resistance is helpful to decrease the consumption in the components. In theory, heat can be calculated by output current and internal resistance. That is to say, these two factors are the primary determinants to heat production.

Third, a good design of heat dissipation should be taken into account. Normally, the adapters with the output power above 100W have metallic perforated shells or cooling fans. Besides, the adapter with larger heat dissipating surface is better to users.

Comparatively, as heat has been weakened by the canning materials, temperature of surface is lower than that inside the ac adapter. Therefore, when using the laptop charger, keep it away from inflammable goods like bedclothes and books.

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by: USB Phone World